In May and June of 2015, a team put together by the Geotechnical Extreme Events Reconnaissance (GEER) Association visited Nepal to evaluate the geotechnical damage and effects spurred by the recent earthquake sequence. Landslides, ground failures, damage to hydropower projects, roadways, bridges and buildings were among the features observed. A report of the team’s findings, complete with photos and preliminary analyses, is available on the GEER Association website through the link below:

Updated Map of Landslides Triggered by Ghorka Earthquake and Aftershocks

Posted by Patrick Bassal and Ashly Cabas

7/6/15

An updated landslide intensity map (including landslides caused by both the 25 April Ghorka Earthquake and the 12 May Dolakha Earthquake) has been posted to the Earthquakes without Frontiers blog. Approximately 5600 landslides have been mapped as of 10 June 2015.

Landslides have been a major problem since the earthquakes hit in Nepal. AGU’s landslide blog has a recent update concerning the Araniko Highway (a major link connecting Nepal with Tibet and China). Much of the highway has been littered with landslide debris, thus shutting down a necessary trade route. As the monsoon season is just underway, it will be critical to stay aware of the imminent landslide risks they may pose.

Some of the latest information concerning landslides in Nepal is being continuously updated in the following blogs:

Some researchers at the University of Michigan (U-M) have performed an analysis of landslide hazards associated with the recent Nepal earthquakes. Their analysis of landslide risk was performed using a computer analysis that looked at the earthquake ground motions, slope steepness, and strength of rock types. Their website contains downloadable “.kmz” files depicting the areas that may have experienced landslides or have an increased risk of landslides due to the earthquakes.

“Information from the U-M-led study has been shared with the U.S Geological Survey, NASA, the U.S. Agency for International Development and other responding agencies. It is being used help prioritize both satellite observations and the analysis of data from those satellites, said Clark, an associate professor in the U-M Department of Earth and Environmental Science.”

More information and downloadable content is provided in the links below:

Research groups in the UK have been working to identify large landslides that are blocking valleys, affecting villages, and disrupting the infrastructure in Nepal. Their observations are based on satellite imagery taken from multiple sources (see map posted below). Their preliminary findings and recommendations for field study can be found in the Earthquakes Without Frontiers link below. One of the most significant observations is that the zone mapped to have intense landsliding corresponds to areas with high rates of past landslides triggered by rainfall. It is thus necessary to assess the hazard associated with these potential landslides before the upcoming monsoon season, expected to start in late June.

Natural and human-induced landsliding in the Garhwal Himalaya of northern India
Patrick L. Barnard, Lewis A. Owen, Milap C. Sharma, Robert C. Finkel
Geomorphology 40 (2001) 21-35
This paper looks at the effects of a M 6.6 earthquake that took place March 28th, 1999 in the Garhwal Himalaya. “The earthquake was focused ~10.8 km WNW of Camoli (30.49 degrees N, 79.29 degrees E) at a depth of ~15km.”
Within the study area, the earthquake initiated about 50 small landslides. The setting of this study is very close to Nepal, and appears to have a very similar geological setting.

Trends in landslide occurrence in Nepal 2007
David N. Petley, Gareth J. Hearn, Andrew Hart, Nicholas J. Rosser, Stuart A. Dunning, Katie Oven, Wishart A. Mitchell
October 2007, Volume 43, Issue 1, pp 23-44
Natural Hazards
“The aim of the study reported here is to compile and evaluate data regarding the temporal trends in landslide occurrence in Nepal in the period 1978-2005 and to use these data to attempt to understand the underlying causes of changes in landslide impacts through time.”

EERI Reconnaissance Team Findings

EERI Team Report ReleasedThe 185-page report describes the findings of a multidisciplinary reconnaissance team sent to Nepal by EERI’s Learning from Earthquakes program.

Watch the EERI Reconnaissance Briefing WebinarsThe video playlist features an introduction on EERI’s response, presentations in different topic areas by each member of the team that visited Nepal in June 2015, and a summary of the mission’s findings. Briefing videos range in duration from 10 to 35 minutes, and can be watched individually or in a series.

View EERI Photo GalleryThese photos were taken by members of the EERI reconnaissance team that traveled to Nepal in June 2015. The photos are viewable through the photo gallery and within the map, below.